man: in the 1993 cryptosporidium outbreak, over 400,000 people became ill with diarrhea, cramping and nausea, and we also recorded over 100 deaths, primarily in the immuno-compromised community, and in particular, individuals with aids, or hiv infection. man: people were beginning to experience symptoms of diarrhea. it started to become more and more widespread. so the natural spot to look was drinking water. so tests were run on the water coming out of both of our water treatment plants. and we found cryptosporidium coming out of our howard avenue plant. man: milwaukee officials are shutting down one of the city's two water purification plants. biedrzycki: cryptosporidium is a parasite that's found in the gut or intestine of both humans and animals, and found in many surface waters throughout the globe. prior to 1993, it was not on our radar. it was not a reportable disease. narrator: epa standards did not safeguard against cryptosporidium, because it was an unknown threat. once it contaminated the water supply, the treatment plant had no capability to kill the pathogen. so it spread throug